Vaccines for dementia: 4 vaccines that can lower the risk of the progressive disease

Dementia remains one of the world’s most urgent public health challenges. It’s an umbrella term used to describe a range of neurological conditions affecting the brain that worsen over time, and there are currently over 55 million people with dementia worldwide, with nearly 10 million new cases of dementia developing each year. The number of people with dementia is growing worldwide and is expected to triple by 2050.

This common and disabling disease that affects the brain occurs when brain cells are damaged or die, leading to progressive declines in cognitive functions, mood, behavior, and personality. Common forms include Alzheimer's disease, vascular dementia, and dementia with Lewy bodies, and while there is no cure, treatments and lifestyle changes can help manage symptoms and improve quality of life.

However, new research shows that certain vaccines, already in use for other diseases, may also help reduce the risk or delay the onset of dementia. In fact, recent studies from the University of Oxford, NIHR, Stanford, and others show that vaccines like those for shingles, respiratory syncytial virus (RSV), influenza, pneumococcus, and Tetanus-Diphtheria-Pertussis (Tdap) may lower the chance of developing dementia.

Knowing which vaccines, how much protection, who should take them, and when could help millions protect their brain health.

What the evidence says: Multiple observational studies and a meta-analysis show that people aged 60-65 and older who get annual flu shots are less likely to develop dementia. For example, a large US veteran cohort found that repeated flu vaccination reduced dementia risk compared to those who didn’t take the vaccine. In one study, older adults who had at least one flu vaccine were about 40% less likely to develop Alzheimer’s disease over four years.

Who can take it: Most countries already recommend flu vaccines for seniors and people with certain health conditions.

When to take it: Yearly. The data show that more frequent flu shots (over many years) give stronger protection.

What the evidence says: A major study led by the University of Oxford found that Shingrix (a newer, more effective shingles vaccine) was associated with about 17% lower risk of dementia over six years compared to the older Zostavax vaccine. Additionally, Shingrix had a 23-27% lower dementia risk than vaccines for flu, tetanus, diphtheria, or pertussis in some comparisons.

Who can take it: Older adults (often aged 60-65 and above, depending on country rules), especially those who had chickenpox earlier (which is necessary for shingles risk).

When to take it: Usually one or two doses (depending on vaccine guidelines), ideally before shingles risk becomes high (often in the elderly). Consistent vaccine uptake seems key. Earlier vaccination gives benefits.

What the evidence says: The vaccine Arexvy (against respiratory syncytial virus, RSV) has been linked with a 29% reduction in dementia diagnoses within 18 months among adults over 60. It contains the same adjuvant (called AS01) as Shingrix, which is thought to boost immune system activity in a way that may protect brain health.

Who can take it: Adults over 60 are eligible in places where the RSV vaccine is approved and offered.

When to take it: When the vaccine is made available; likely as a one-time dose or maybe boosters in the future (depending on guidance).

What the evidence says: Studies show that pneumonia vaccines (for example, pneumococcal) and vaccines like Tdap may also be associated with reduced dementia risk. The Alzheimer’s Association cited research where pneumonia vaccination between the ages of 65 and 75 reduced Alzheimer’s risk by up to 40% in certain groups. In meta-analyses, influenza vaccination in high-risk groups (chronic kidney disease, vascular disease, etc.) also shows a stronger protective link.

Who can take them: Older adults (usually 65+), people with risk factors for pneumonia or chronic illness; guidelines vary by country.

When to take it: Generally, as per adult vaccination schedules, often once or with periodic boosters, especially before older age or when risk rises.

While vaccines are made to protect against specific infections, researchers believe several mechanisms might explain their effects on dementia:

Reducing infections and inflammation: Frequent infections, especially respiratory viruses or viruses like herpes zoster (shingles), can trigger chronic inflammation that harms brain cells. Vaccines reduce both the chance and severity of infections.

Stimulating the immune system in beneficial ways: Some vaccines contain adjuvants — substances that boost immune responses. For example, the AS01 adjuvant in Shingrix and Arexvy might activate immune cells in ways that protect brain health beyond just fighting the infection.

Delaying onset or progression: By reducing the cumulative burden of insults (infections, inflammation, immune stress), such vaccines may delay when dementia symptoms appear, or possibly slow progression.